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![Study site map. Map of the northern Gulf of Mexico. Geographical reference points include Galveston Bay (GB), Atchafalaya Bay (AB), Terrebonne Bay (TB), the Louisiana Bight (LB) and the six bordering states. Mobile Bay and Sabine Pass mark the eastern and western extent of the "Fertile Fisheries Crescent" [12]. The Texas shelf is outlined in green and the Louisiana-Mississippi shelf is outlined in yellow.](publication/319280117/figure/fig1/AS:614182147862540@1523443843484/Study-site-map-Map-of-the-northern-Gulf-of-Mexico-Geographical-reference-points-include.png)
Study site map. Map of the northern Gulf of Mexico. Geographical reference points include Galveston Bay (GB), Atchafalaya Bay (AB), Terrebonne Bay (TB), the Louisiana Bight (LB) and the six bordering states. Mobile Bay and Sabine Pass mark the eastern and western extent of the "Fertile Fisheries Crescent" [12]. The Texas shelf is outlined in green and the Louisiana-Mississippi shelf is outlined in yellow.
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The northwestern Gulf of Mexico shelf experiences one of the largest seasonal hypoxic zones in the western hemisphere. Hypoxia (dissolved oxygen, DO ≤ 2.0 mg·L⁻¹) is most severe from May to August during the height of the Gulf shrimp fishery, but its effects on the fishery are not well known. Prior studies indicate that hypoxia alters the spatial d...
Citations
... ). We are not aware of similar studies in the Gulf of Mexico, but reduced fishing effort by commercial shrimp trawls during the 2000s(Gallaway et al. 2020;Purcell et al. 2017) may explain higher sea pen CPUE in recent years.Tube-building polychaetes were not wellrepresented in the trawl data, thus it is not known whether there has been any change in abundance. These polychaetes and the various other benthic organisms associated with their tubes were a commonly observed finding in thePlotkin et al. study (1993) and were the most frequently observed prey type in loggerheads affected during the 2022 event.Another environmental factor related to the abundance and distribution of prey is the large hypoxic zone that occurs in the northern Gulf of Mexico every summer, and is the largest within US waters. ...
... High-nutrient runoff from agricultural lands (Withers et al., 2014) and urban areas (Tromboni and Dodds, 2017;Wurtsbaugh et al., 2019) are the main causes of coastal eutrophication (Paerl et al., 1998) which can stimulate harmful algal blooms (HABs) that cause millions of dollars in damages annually (Hamilton et al., 2009;Heil and Muni-Morgan, 2021;Kouakou and Poder, 2019;Smith et al., 2019), and accelerated deoxygenation of the coastal ocean (Harrison et al., 2017;Young et al., 2020). In the northern Gulf of Mexico (GoM), an annually recurring 'dead zone', a direct result of nitrogen pollution from the Mississippi Atchafalaya River Basin (Rabalais and Turner, 2001;Rabalais et al., 1999Rabalais et al., , 2002Robertson and Saad, 2013), negatively impacts the economics of fisheries (Craig, 2012;Craig et al., 2005;Purcell et al., 2017). ...
... Lack of oxygen in seawater may cause fish death, leading to changes in fish distribution due to migration to avoid hypoxia stress [47]. Purcell et al. [48] integrated the geographic distribution of dissolved oxygen in the northwestern Gulf of Mexico to assess the effect of hypoxia on the spatial pattern of shrimp fishing effort. The results suggest that hypoxia changes the spatial dynamics of shrimp fisheries in the Gulf of Mexico, affecting the catch volumes and the economic status of fisheries. ...
Monitoring and understanding the behavior of fishing vessels are important in facilitating effective management, preventing illegal fishing, informing fishing grounds and evaluating effects of harvests on fishery resources. In recent decades, a large quantity of real-time data of fishing vessels have become available with the development of vessel-tracking systems, making it possible to study the behavior of fishing vessels in high spatial and temporal resolutions. To effectively and efficiently deal with the large amount of data, algorithms from artificial intelligence (AI) are increasingly applied in the study of fishing vessel behavior. In this paper, we first introduce the various data sources for studying fishing vessel behavior and compare their pros and cons. Secondly, we review the AI methods that have been used to monitor and extract the behavior of fishing vessels from big data. Then, studies on the physical, ecological and social mechanisms affecting the behavior of fishing vessels were synthesized. Lastly, we review the applications of fishing vessel behavior in fishery science and management.
... 89 Eutrophication that contributes to the development of HABs in summer months also promotes the development of hypoxia in coastal waters, 90 which can have a devastating impact on commercial fishing. [91][92][93][94] The hypoxic zone off the Louisiana coast is the second largest human-caused coastal hypoxic area in the global ocean. Such conditions have been found year round but are mostly seasonal especially in summer, for example, on the Gulf Coast 95, 96 where the Gulf of Mexico Coastal Ocean Observing System (GCOOS) has been charged with the task of monitoring and quantifying the extent of hypoxic "dead zones". ...
... Shifting fishing outside the affected region can concentrate activity in undisturbed areas and result in competition, social conflict and resource depletion (Lewis, 1996;Hiddink et al., 2006). Although a large body of literature has described fisheries displacement due to spatial closures such as management closures (e.g., Abad et al., 2010;Grüss, 2014;Chollett et al., 2016;Bastardie et al., 2020), we have been able to find very few examples of studies quantifying fisheries displacement in response to environmental disturbances (Purcell et al., 2017). ...
Red tides have affected marine and coastal communities for centuries. The effects of red tides on commercial capture fisheries have rarely been evaluated, owing in part to a lack of appropriate data. Leveraging modeled maps of red tide severity, vessel monitoring systems data, and logbook records, we investigated the commercial fisheries impacts of red tide events in Florida during the period 2008–2019. We focused on the bottom longline and vertical line fisheries targeting reef fishes. Red tides were punctuated events peaking at the end of summer, with 2018 and 2019 the most intense years. The total area affected by intense red tides (concentrations> 1,000 cells/L) was 103,483 km2, about the size of the state of Kentucky. Red tides did not have negative effect on fleet- level fisheries metrics such as number of fishing vessels, trips, fishing effort or revenue (generalized mixed effect models, p > 0.5). Fishing effort was, however, displaced from the red tide areas, and fishers avoided areas characterized by intense blooms (zero-inflated negative binomial model, p < 0.001). Follow up of the long-term likely responses of the resource and the catch are needed to fully understand the consequences of red tide events in commercial fisheries in the Gulf of Mexico.
... Hypoxia has also been demonstrated to alter catch and effort patterns. Purcell et al. (2017) showed that hypoxiainduced changes in the distribution of shrimp also alter the spatial dynamics of the Gulf of Mexico shrimp fleet, with potential consequences for harvest interactions and the economic condition of the fishery. Bio-economic simulations of the Gulf shrimp trawl fishery suggest that hypoxia can lead to both short-term increases or decreases in catch, depending on the effects of hypoxia on components of shrimp production (e.g. ...
Mobile bottom contact gear such as trawls is widely considered to have the highest environmental impact of commonly used fishing gears, with concern about impact on benthic communities, bycatch, and carbon footprint frequently highlighted as much higher than other forms of fishing. As a result, the use of such gears has been banned or severely restricted in some countries, and there are many proposals to implement such restrictions elsewhere. In this paper, we review the sustainability of bottom trawling with respect to target-species sustainability, impact on benthic communities, bycatch and discards, carbon footprint from fuel use, and impact on carbon sequestration. We compare the impact to other forms of fishing and other food production systems. We show that bottom-trawl and dredge fisheries have been sustained, and where well managed, stocks are increasing. Benthic sedimentary habitats remain in good condition where fishing pressure is well managed and where VME and species of concern can be protected by spatial management. Bycatch is intrinsically high because of the mixed-species nature of benthic communities. The carbon footprint is on average higher than chicken or pork, but much less than beef, and can be much lower than chicken or pork. The impact on carbon sequestration remains highly uncertain. Overall, the concerns about trawling impacts can be significantly mitigated when existing technical gear and management measures (e.g. gear design changes and spatial controls) are adopted by industry and regulatory bodies and the race-to-fish eliminated. When these management measures are implemented, it appears that bottom trawling would have a lower environmental impact than livestock or fed aquaculture, which would likely replace trawl-caught fish if trawling was banned. A total of 83 bottom-trawl fisheries are currently certified by the Marine Stewardship Council, which is the most widely accepted measure of overall sustainability.
... These forage taxa, unlike most of the NES forage taxa, comprise important regional fisheries that may be spatially impacted by OSW structures. To further complicate the development of spatial planning to accommodate fishing interests, the distributions of both fisheries are impacted by the distribution of oxygen levels in the Gulf of Mexico (Langseth et al. 2014;Purcell et al. 2017). Without looking very hard, we see ample evidence that different regions will pose species-specific spatial planning challenges to ameliorate ecosystem and fisheries concerns with the installation of OSW structures. ...
As the world develops sources of renewable energy, there is an intensifying interest in offshore wind energy production. The Northeast U.S. Continental Shelf (NES) ecosystem has favorable wind dynamics, with active development of wind energy. In this study, we present species distribution models that consider both occupancy and biomass responses for a broad spectrum of fish and macroinvertebrate taxa (n = 177). Building upon prior analyses, habitat was differentiated into overall and core habitats based on statistical distributions of habitat scores. Overall habitat was used to show each species' regional distribution based on fishery-independent survey captures between 1976 and2019, whereas core habitat represented where the focus of the species' abundance was located as a subset of overall habitat. Wind energy developments may modify the water column in ways that impact lower-trophic-level productivity; therefore, added attention was given to the response of forage species. Over 20% of species showed preferential use of putative and potential wind development areas, including a disproportionate number of forage taxa. Principal usage varied by season, with forage species like Atlantic Menhaden Brevoortia tyrannus and Atlantic Mackerel Scomber scombrus preferentially using the lease areas in spring and Round Herring Etrumeus teres and longfin inshore squid Doryteuthis pealeii using lease areas in autumn. For species with relatively low usage of the lease areas, there was a tendency for the usage related to overall habitat to be lower than usage for core habitat; in contrast, for species with high usage of the lease areas, that usage was higher for overall habitat than for core habitat. The area of habitat tended to have positive trends across species, with these positive trends being disproportionately higher among forage taxa. These results frame the importance of wind lease areas for species in the NES, particularly forage taxa that fulfill many important ecological functions.
... According to this study, the average final FCR during the experimental period for Aqualis and Topfeed was 1.02 and 1.11, respectively. This difference may be caused by environmental factors, fish activity levels, and fish sizes (Purcell et al., 2017). Using the stated FCR benchmark for the rearing of Catfish, 1.11 according to Ayoola and Abdul (2016), who acquired an FCR of 1.25, which is comparable, it can be concluded that both feeds performed well. ...
The feed trial was carried out in African Inland Fish Farming Limited, Ibeju-lekki Lagos State, Nigeria to assess the growth of Clarias gariepinus fed with two commercial diets. Using a complete randomized design and six treatments separated into T1 and T2, the feed trial was carried out to assess the growth performance of two commercial fish feeds (Aqualis and Topfeed) on Clarias gariepinus for a period of 55 days using circular tarpaulin tanks with a capacity volume of 28.3 m3 marked DS1, DS2, ES1, ES3, ES4, and FS1 stocked with 11,250/tank juveniles with an initial weight of 8.0 g were stocked in each tank. Fish in units ES3, ES4, and FS1 were fed Topfeed whereas fish in units DS1, DS2, and ES1 were fed Aqualis feed. Feeding was done twice daily. All physicochemical parameters were assessed using the Sera Aqua-Test Kit and the dry matter of the two commercial diets underwent chemical analysis. The growth performance parameters revealed that the final mean weight (g), mean weight gain (MWG) (g), specific growth rate (SGR), and survival rate were not significantly different between the two feeds (p>0.05). The results demonstrated that Topfeed outperformed Aqualis feed with a higher survival rate and a feed conversion ratio (FCR) value of (p>0.05). Also, the proximate composition revealed no significant differences (p>0.05) between the two feeds. Based on the findings, it can be said that Topfeed outperformed Aqualis feed for raising C. gariepinus.
... For example, habitats of some fish species (e.g., croaker and brown shrimp) shift to offshore hypoxic edges (Craig and Crowder, 2005;Craig, 2012) during summer hypoxia events, which may impact organism energy budgets and trophic interactions (Craig and Crowder, 2005;Hazen et al., 2009). The horizontal displacement of habitats of brown shrimp in summer can also lead to changes in the distribution of Gulf of Mexico shrimp fleets (Purcell et al., 2017). Although an action plan has been launched by the Mississippi River/Gulf of Mexico Hypoxia Task Force to control the size of the midsummer hypoxic zone below 5000 km 2 in a 5-year running average since 2001 (Mississippi River/Gulf of Mexico Watershed Nutrient Task Force, 2001, extents of the hypoxic area have experienced no significant decreases in recent decades (Del Giudice et al., 2020). ...
This study presents a novel ensemble regression model for forecasts of the hypoxic area (HA) in the Louisiana–Texas (LaTex) shelf. The ensemble model combines a zero-inflated Poisson generalized linear model (GLM) and a quasi-Poisson generalized additive model (GAM) and considers predictors with hydrodynamic and biochemical features. Both models were trained and calibrated using the daily hindcast (2007–2020) by a three-dimensional coupled hydrodynamic–biogeochemical model embedded in the Regional Ocean Modeling System (ROMS). Compared to the ROMS hindcasts, the ensemble model yields a low root-mean-square error (RMSE) (3256 km2), a high R2 (0.7721), and low mean absolute percentage biases for overall (29 %) and peak HA prediction (25 %). When compared to the shelf-wide cruise observations from 2012 to 2020, our ensemble model provides a more accurate summer HA forecast than any existing forecast models with a high R2 (0.9200); a low RMSE (2005 km2); a low scatter index (15 %); and low mean absolute percentage biases for overall (18 %), fair-weather summer (15 %), and windy-summer (18 %) predictions. To test its robustness, the model is further applied to a global forecast model and produces HA prediction from 2012–2020 with the adjusted predictors from the HYbrid Coordinate Ocean Model (HYCOM). In addition, model sensitivity tests suggest an aggressive riverine nutrient reduction strategy (92 %) is needed to achieve the HA reduction goal of 5000 km2.
... Our analysis indicates that the greatest percent reductions in hypoxic area and volume following nutrient load reductions occurred in the East-Shelf region. This commonly hypoxic region south of Terrebonne Bay is noted for distinct spatial shifts in brown shrimp populations (Craig, 2012;Craig and Bosman, 2013) and subsequent low effort shrimping efforts (Purcell et al., 2017). Although less impactful to shelfwide hypoxia, incremental nutrient load reductions below those needed to achieve the 5000 km 2 goal may yield improved habitat suitability in this region of the shelf. ...
Complex simulation models are a valuable tool to inform nutrient management decisions aimed at reducing hypoxia in the northern Gulf of Mexico, yet simulated hypoxia response to reduced nutrients varies greatly between models. We compared two biogeochemical models driven by the same hydrodynamics, the Coastal Generalized Ecosystem Model (CGEM) and Gulf of Mexico Dissolved Oxygen Model (GoMDOM), to investigate how they differ in simulating hypoxia and their response to reduced nutrients. Different phytoplankton nutrient kinetics produced 2–3 times more hypoxic area and volume on the western shelf in CGEM compared to GoMDOM. Reductions in hypoxic area were greatest in the western shelf, comprising 72% (∼4,200 km²) of the total shelfwide hypoxia response. The range of hypoxia responses from multiple models suggests a 60% load reduction may result in a 33% reduction in hypoxic area, leaving an annual hypoxic area of ∼9,000 km² based on the latest 5-yr average (13,928 km²).
